My interpretation:
2 oz Castle & Key London Dry Gin
2 dashes Jack Rudy Grenadine
1 slice fresh ruby grapefruit (for shaker)
1 half slice ruby grapefruit (for garnish)
Fill mixing-glass half-full with ice, shake 10 seconds, double strain into cocktail glass, garnish with fresh half-slice ruby grapefruit. — A nice refreshing Sour with grenadine for sweetener. The inclusion of the peel in the shaker allows some of the oils from from the peel to mix with the liquid, producing a fuller bouquet and spectrum of flavors. Whether C. O. D. stands for Cash On Delivery or something else is unclear.
